Did you trying to repair your installation?
In a folder something like
C:\Program Files\SOLIDWORKS Corp\SOLIDWORKS\Toolbox\data utilities
there's a program called "UpdateBrowserDatabase". Run that.
Please note - if your database is shared on the network with other users still on 2017, this will ruin it for them.
Before you update the database, I recommend to copy the existing Toolbox folder. You can destroy it after testing that everything with the new one is OK.